1. Field of the Invention
This invention relates to internal combustion engines, and more particularly to an improvement in engines of the type employing main and auxiliary pistons.
2. Prior Art
The internal combustion engine of the present invention differs in significant regard from prior conventional internal combustion engines of the two stroke cycle and four stroke cycle types. However, certain terminology developed with reference to such previously known engines is of value in clarifying the operation of the engine of this invention.
The quasi harmonic motion of a piston operatively connected to a crankshaft has given rise to such terminology as "top dead center" (TDC) and "bottom dead center" (BDC) positions of a piston. Top dead center position refers to a position of the piston, connecting rod and crankshaft in which the axis of rotation of the crankshaft and the axis of pivotal connection of the connecting rod with the piston and the crankshaft are aligned while the piston is at its furthest distance from the center of the rotation of the crankshaft. Bottom dead center is the position in which the axis of rotation and pivotal movement are aligned while the piston is in its position of most close approach to the center of rotation of the crankshaft. Another term used in a conjunction with conventional internal combustion engines is "displacement" meaning the volume swept by a piston in one stroke. Prior engines are described hereinafter.
Bundrick, Jr., U.S. Pat. No. 4,419,969, is directed to an internal combustion engine with manual adjustable cylinder compression. Opposing pistons are shown with one crank having a third larger crank than the other.
Davis, U.S. Pat. No. 4,190,024, discloses a variable chamber diesel engine. The engine is two cycle with a glow plug to ignite fuel and has means for varying the combustion chamber.
Faulconer, Jr., U.S. Pat. No. 4,169,435, discloses an internal combustion engine. The engine includes opposing pistons and operate in a manner to maintain increased pressure on the power piston through the combustion stroke. There is an upper piston which moves through a complex motion to create a super charged engine. Faulconer, Jr. also mentions a constant volume during the combustion phase.
Radovic, U.S. Pat. No. 3,312,206, discloses a reciprocating engine for increasing power. The engine includes a cam actuated above a conventional work piston. Radovic mentions a constant volume during the combustion phase.
Rouger, U. S. Pat. No. 3,741,175, discloses a variable compression ratio internal combustion engine for increased power. There is shown an auxiliary piston operating at one half the main piston frequency and a linkage for varying the compression ratio for both two-cycle and four-cycle engines.
Dutry, U.S. Pat. No. 3,868,931, discloses an auxiliary piston rotating at more than twice that of the crankshaft cooperating with the piston of the working cylinder and is preferably three times as great. It would appear the pistons must operate at integer ratios so the cycles can repeat. The claim here seems to be that holding the charge at a constant volume during ignition promotes more complete combustion and less pollutants.
Gustavasson, U.S. Pat. No. 4,143,628, discloses a variable compression ratio engine. The linkage seems to be the focal point of the patent. There appears to be no provisions for valving.
Hale, U.S. Pat. No. 1,574,574, discloses an internal combustion engine, wherein the firing of the charge occurs after TDC to prevent "back kick." This was a problem while hand cranking, prior to the electric starter and the automatic spark timing control. Many an arm, wrist, and hand were broken because someone forgot to "retard the spark" to insure firing after TDC. The auxiliary piston appears to be relatively stationary during the power stroke.
Wolf, U.S. Pat. No. 1,914,707, discloses an internal combustion engine which fires the charge after TDC as a method of increasing the torque on the crankshaft. Two opposing pistons are shown wherein an upper (non power) piston is moved as a function of a cam and cam follower.
Cain, U.S. Pat. No. 1,940,533, discloses a four-cycle internal combustion engine. There is an indication of complete expulsion of the exhaust gases.
Buchwalder, U.S. Pat. No. 2,118,153, discloses an internal combustion engine with an auxiliary piston to optimize on the conventional engine. Through an elaborate and costly mechanism, one power stroke per main crank revolution is obtained. A longer power stroke to intake stroke is also disclosed. A more complete expulsion of the exhaust gases is disclosed as well as the use of ports to carry out the exhaust phase of the mechanism.
While there have been many improvements in the internal engine, there remains a need for more efficient engine. Particularly, improvements of volumetric, lubrication and combustion efficiency are needed. It is also desirable to obtain such efficiencies with manufacturing economy.